gpu: Cache results of GetShaderPrecisionFormat client-side

gpu/command_buffer/client/gles2_implementation.h

Index: gpu/command_buffer/client/gles2_implementation.h
diff --git a/gpu/command_buffer/client/gles2_implementation.h b/gpu/command_buffer/client/gles2_implementation.h
index 7124c7306b785a7a15dab0349b712e5d0e967402..3985c7d9897f530ae27f4f9e018aa48c5114408e 100644
--- a/gpu/command_buffer/client/gles2_implementation.h
+++ b/gpu/command_buffer/client/gles2_implementation.h
@@ -582,6 +582,13 @@ class GLES2_IMPL_EXPORT GLES2Implementation : public GLES2Interface {
 
   scoped_ptr<MappedMemoryManager> mapped_memory_;
 
+  // Cache results of GetShaderPrecisionFormat
+  typedef std::pair<GLenum,GLenum> ShaderPrecisionCacheKey;
+  typedef std::map<ShaderPrecisionCacheKey,
+                   cmds::GetShaderPrecisionFormat::Result>
+      ShaderPrecisionCacheMap;
+  ShaderPrecisionCacheMap shader_precision_cache_;
+
   scoped_refptr<ShareGroup> share_group_;
 
   scoped_ptr<QueryTracker> query_tracker_;